ichimal / cl-syntax

Reader Syntax Coventions for Common Lisp and SLIME

CL-SYNTAX

CL-SYNTAX provides Reader Syntax Coventions for Common Lisp and SLIME.

Overview

The well-known problem about reader macros is that SLIME can't handle these reader macros correctly. Consider the following code:

(defpackage foo
  (:use :cl))
(in-package :foo)
(cl-interpol:enable-interpol-syntax)

(list #?"Current Time: ${(get-universal-time)}")

By calling cl-interpol:enable-interpol-syntax, we can use a reader macro #?. However, actually, when we try to evaluate the last line, SLIME reports an error there is no such the reader macro #?. This error might be raised on most of Common Lisp implementations except SBCL.

The goal of CL-SYNTAX is to solve these problems. Instead of using procedurally defined functions such like enable-something-syntax, we introduce syntactically and declaratively defined syntax data structure. With this data structure, we can handle *readtable* correctly and readtables of swank server.

Usage

Macro: defsyntax

defsyntax name &body options

defsyntax defines a new syntax. name is a symbol and options is a list of option.

If option formed (:macro-character char fn &optional non-terminating-p), the syntax engine will call set-macro-character with the arguments when enabling the syntax.

If option formed (:dispatch-macro-character disp-ch sub-ch fn), the syntax engine will call set-dispatch-macro-character with the arguments when enabling the syntax.

Here is an example:

;; Define cl-interpol syntax
(defsyntax interpol-syntax
  (:dispatch-macro-character #\# #\? #'cl-interpol::interpol-reader))

This code is equivalent to:

(defvar interpol-syntax
    `((:dispatch-macro-character #\# #\? ,#'cl-interpol::interpol-reader)))

If you don't want to use defsyntax in some reasons, use this code instead.

Macro: use-syntax

use-syntax syntax-to-use

use-syntax enables the syntax specified by syntax-to-use. syntax-to-use is a symbol which is defined by defsyntax.

Here is an example:

;; use cl-interpol syntax defined before
(use-syntax interpol-syntax)

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Copyright (C) 2011 Tomohiro Matsuyama <[email protected]>